The present invention relates to a vehicle brake rotor and more specifically to a brake rotor having improved vibration damping characteristics.
Wheeled vehicles are typically slowed and stopped with a braking system that generates frictional forces. One known braking system is the disc brake system which includes a rotor attached to one or more of the vehicle wheels for rotation therewith. Rotors typically include a central hat section for attaching the rotor to the vehicle, and an outer friction section having opposite, substantially parallel friction surfaces.
The disc brake assembly further includes a caliper assembly secured to a non-rotating component of the vehicle for moving friction members, such as brake pads, into contact with the rotor friction surfaces. During braking, the brake pads press against the moving rotor friction surfaces creating frictional forces which oppose the rotation of the wheels and slow the vehicle.
Brake rotors are typically cast from an electrically conductive material, preferably a ferrous material such as cast iron or gray iron, and are then machined to achieve the desired dimensions and tolerances. During conventional machining, a tool is pressed against the rotor to remove a portion of the surface of the rotor, such as the friction surface.
Unwanted noise and vibrations are often created during braking with conventionally machined rotors. The disc brake system components, such as the caliper and brake pads, vibrate during braking. This vibrational energy is transferred to the rotor which is also known as exciting the rotor. The excited rotor vibrates with the greatest amplitude at or near it""s resonant frequencies producing undesirable audible noises such as xe2x80x9csquealxe2x80x9d.
It is desirable to increase the damping of the rotor to reduce the noise and vibration from the rotor during braking.
The invention relates to a brake rotor having improved damping characteristics and a method for producing the same. The brake rotor includes a friction section having a friction surface for interfacing with a brake component such as a brake pad during braking. A surface of the brake rotor is EDG machined, also known as EDM machined, for improving the damping characteristics of the rotor. The decay rate of the brake rotor is increased and the Q factor of the brake rotor is reduced.
The portion of the brake rotor which is EDG machined is formed of an electrically conductive material, preferably a ferrous material, more preferably a cast iron material, a gray iron material or a damped iron material. The brake rotor may include a solid friction section or a ventilated friction section. The brake rotor is preferably cast from a single material, although alternatively, it may be a composite rotor formed of more than one material.
A method for improving a brake rotor""s damping characteristics, includes increasing the decay rate and/or reducing the Q factor by EDG machining or EDM machining a surface of the rotor. The EDG or EDM machining preferably includes providing at least one electrode and reducing the distance between the electrode and the rotor surface until one or more sparks extend therebetween. The surface is preferably the friction surface although any suitable surface of the brake rotor may be EDG or EDM machined to improve the rotor""s damping characteristics.